This invention relates generally to a tumbling mill for new castings, and in particular to a tumbling mill with improved sand reclaiming abilities.
Various types of tumbling devices or mill for removing mold sand from casting, or for separating other particles or fragments from castings or other metal parts have long been available in the art. For example, my prior patent, U.S. Pat. No. 4,674,691, which is incorporated herein by reference, discloses a tumbler including a sand reclaimer which will return sand and media from the outlet area of the tumbler to the inlet area, where the media can be reintroduced into the tumbler. In my prior patent, U.S. Pat. No. 5,267,603, which is also incorporated herein by reference, I disclose another tumbler, which also includes a media and sand return system. This tumbler, however, is provided with a screen classifier which will allow small particles of sand to fall through a screen. The screen is provided at the inlet area of the tumbler and is housed in a casing. The sand which passes through the screen exits the tumbler through a chute in the housing. The screen surrounds the segmented inner liner and thus performs two functions: (1) it screens the sand so that small particles of sand will fall through and so that media and larger particles of sand will be reintroduced into the tumbler; and (2) it holds the segmented liner together in the intake area of the tumbler.
The segments are interlocked with each other, as described in my application Ser. No. 08/323,010, which is incorporated herein by reference. However, when a large number of heavy castings, such as engine block castings, are introduced into the tumbler, the tumbling of the castings within the unit may cause the segments to separate, either radially or horizontally. This can lead distorting of the screen. Eventually, the screen will have to be replaced, so that the intake section will be able to be held together.